Systems for automatic content recognition (ACR) of audio or video media are well known to persons skilled in the art. However, such ACR systems pose many technical challenges, including managing potentially very large databases of encoded audio or video information as well as managing large indices needed for addressing information in said databases.
Also well known to those skilled in the art, is that large database indices such as may be used by this invention, can be generated using certain hashing functions. Another method of addressing a database might be by applying binary tree structures also known as b-trees. Both methods are commonly utilized in data management systems.
Whatever the method employed to index a large database, said index is often too large to reside in its entirety in the main memory of a computer server as used in a typical ACR system. When said database cannot fit entirely in the memory of a computer system, it is typically stored on magnetic disk storage and parts of said database are then read into memory in blocks corresponding to the index value providing the address. Said means of recalling partial database information is also known to one skilled in the art as “paging” which is a process common to many different computer software systems.
The present invention is an extension of the invention referenced above and is a system and method for matching unknown digital media such as television programming to a database of known media using a signal processing means employing a modified path pursuit algorithm, as described in the first invention.
Another novel aspect of the system and method as disclosed herein is its distance associative hash indexing means which can be subdivided into a plurality of independently addressable segments where each of said segments can address a portion of the database each of which can reside in its entirety in the main memory of a server means. The resulting cluster of servers of the indexing means each hosts a sector of the index addressing associated data of a larger database of searchable audio or video information. This indexing means of the invention results in a significant improvement in the speed and accuracy of the ACR system so enabled as to identify unknown media even when the television display is showing content where a user is changing channels, rewinding, fast-forwarding or even pausing video from a digital video recorder.